Several types of antennas intended for integration in mobile terminals are available today. The most common type is the so-called PIFA (Planar Inverted F Antenna) antenna. These antennas normally consist of a radiator element made of metal sheet or flex-film applied to a plastic carrier mounted at a certain distance above ground. Other types exist, all having in common that they are integrated inside the covers of the phone and taking up valuable space.
In mobile terminals of today there is a requirement for more compact terminals and above all thinner terminals which is of special interest for mobile terminals such as mobile phones.
Solutions to integrate the radiating elements of the terminal in the outer cover have therefore been proposed. In this way the number of components is reduced and the thickness of the cover can be used to separate the radiator from the ground as far as possible which is positive for a good antenna performance. This also makes it possible to reduce the thickness of the phone as the cover, including the radiator, becomes part of the antenna. This means that no space is required inside the cover for the radiator as is the case with conventional solutions, thus making the phone thinner.
EP 1439603 proposes a solution with an antenna radiator integrated in a cover and fed through a special feeding element.
A problem with integrating the antenna radiator in the cover in prior art solutions is that it will become more sensitive to influences from the hand of the user of the mobile terminal. Both the signal strength and frequency of the antenna will be affected when the hand covers the antenna or part of the antenna causing a reduced coverage area for the antenna, and possibly a dropped call, as well as reduced talk time as the terminal has to increase output power to compensate for the decreased antenna performance.
Thus there is a requirement for an improved antenna performance where the antenna radiator is integrated in the cover to a mobile phone.